Added user mode support and monitor_writeDec

3 files changed, 55 insertions, 2 deletions

diff --git a/src/kernel/mem/gdt.c b/src/kernel/mem/gdt.c
index 5aaad41..18a5fa7 100644
--- a/src/kernel/mem/gdt.c
+++ b/src/kernel/mem/gdt.c
@@ -3,12 +3,18 @@
 #include <core/monitor.h>
 
 extern void gdt_flush(uint32_t);	//ASM (idt_.asm)
+extern void tss_flush();
 
-#define GDT_ENTRIES 5
+#define GDT_ENTRIES 6
 
+static struct tss_entry tss_entry;
 static struct gdt_entry gdt_entries[GDT_ENTRIES];
 static struct gdt_ptr gdt_ptr;
 
+void gdt_setKernelStack(uint32_t esp0) {
+	tss_entry.esp0 = esp0;
+}
+
 static void gdt_setGate(int num, uint32_t base, uint32_t limit, uint8_t access, uint8_t gran) {
 	gdt_entries[num].base_low = (base & 0xFFFF);
 	gdt_entries[num].base_middle = (base >> 16) & 0xFF;
@@ -20,6 +26,20 @@ static void gdt_setGate(int num, uint32_t base, uint32_t limit, uint8_t access,
 	gdt_entries[num].access = access;
 }
 
+static void gdt_writeTss(int num, uint32_t ss0, uint32_t esp0) {
+	uint32_t base = (uint32_t)&tss_entry;
+	uint32_t limit = base + sizeof(struct tss_entry);
+
+	gdt_setGate(num, base, limit, 0xE9, 0);
+
+	memset(&tss_entry, 0, sizeof(struct tss_entry));
+
+	tss_entry.ss0 = ss0; tss_entry.esp0 = esp0;
+
+	tss_entry.cs = 0x0b;
+	tss_entry.ss = tss_entry.ds = tss_entry.es = tss_entry.fs = tss_entry.gs = 0x13;
+}
+
 void gdt_init() {
 	gdt_ptr.limit = (sizeof(struct gdt_entry) * GDT_ENTRIES) - 1;
 	gdt_ptr.base = (uint32_t)&gdt_entries;
@@ -29,8 +49,10 @@ void gdt_init() {
 	gdt_setGate(2, 0, 0xFFFFFFFF, 0x92, 0xCF);	//Kernel data segment
 	gdt_setGate(3, 0, 0xFFFFFFFF, 0xFA, 0xCF);	//User code segment
 	gdt_setGate(4, 0, 0xFFFFFFFF, 0xF2, 0xCF);	//User data segment
+	gdt_writeTss(5, 0x10, 0);
 
 	gdt_flush((uint32_t)&gdt_ptr);
+	tss_flush();
 
 	monitor_write("GDT ok\n");
 }
diff --git a/src/kernel/mem/gdt.h b/src/kernel/mem/gdt.h
index aac16bb..485002b 100644
--- a/src/kernel/mem/gdt.h
+++ b/src/kernel/mem/gdt.h
@@ -17,7 +17,38 @@ struct gdt_ptr {
 	uint32_t base;
 } __attribute__((packed));
 
+struct tss_entry {
+	uint32_t prev_tss;   // The previous TSS - if we used hardware task switching this would form a linked list.
+	uint32_t esp0;       // The stack pointer to load when we change to kernel mode.
+	uint32_t ss0;        // The stack segment to load when we change to kernel mode.
+	uint32_t esp1;       // Unused...
+	uint32_t ss1;
+	uint32_t esp2;
+	uint32_t ss2;
+	uint32_t cr3;
+	uint32_t eip;
+	uint32_t eflags;
+	uint32_t eax;
+	uint32_t ecx;
+	uint32_t edx;
+	uint32_t ebx;
+	uint32_t esp;
+	uint32_t ebp;
+	uint32_t esi;
+	uint32_t edi;
+	uint32_t es;         // The value to load into ES when we change to kernel mode.
+	uint32_t cs;         // The value to load into CS when we change to kernel mode.
+	uint32_t ss;         // The value to load into SS when we change to kernel mode.
+	uint32_t ds;         // The value to load into DS when we change to kernel mode.
+	uint32_t fs;         // The value to load into FS when we change to kernel mode.
+	uint32_t gs;         // The value to load into GS when we change to kernel mode.
+	uint32_t ldt;        // Unused...
+	uint16_t trap;
+	uint16_t iomap_base;
+} __attribute__((packed));
+
 void gdt_init();
+void gdt_setKernelStack(uint32_t esp0);
 
 #endif
 
diff --git a/src/kernel/mem/paging.c b/src/kernel/mem/paging.c
index 27ce043..d478e05 100644
--- a/src/kernel/mem/paging.c
+++ b/src/kernel/mem/paging.c
@@ -116,7 +116,7 @@ uint32_t paging_fault(struct registers *regs) {
 	}
 
 	if (seg == 0) {
-		monitor_write("(paging.c:119) Unhandled Page Fault ");
+		WHERE; monitor_write("Unhandled Page Fault ");
 		if (regs->err_code & 0x1) monitor_write("present ");
 		if (regs->err_code & 0x2) monitor_write("write ");
 		if (regs->err_code & 0x4) monitor_write("user ");